Java计时器

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这个简单的Java计时器和Java数字时钟的原理差不多,都是利用Java的Timer做计时,然后根据当前的时间生成需要显示的图片或者文字,通过重写paintComponent方法呈现在界面上.

先看看效果:

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基本的工程目录结构如下:

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其中MissionTimerPanel是主要的类,它主要提供了计时器显示数字的绘制,计时器背景的绘制,计时器闪烁的点的绘制,同时使用Swing的Timer使界面的时间发生改变,最终调用Java的重绘,通过paintComponent方法刷新界面.

先写一下它的继承关系：

publicclass MissionTimerPanel extends JPanel implements ActionListener, MouseListener {

看一下它的主要属性字段:

    /** the image of number 0~9 */

    privatefinal BufferedImage[] DIGIT_ARRAY = { createDigit(0),

           createDigit(1), createDigit(2), createDigit(3), createDigit(4), createDigit(5), createDigit(6), createDigit(7), createDigit(8), createDigit(9) };

    /** the image of the dots display */

    privatefinal BufferedImage DOTS_ON = createDots(true);

    /** the image of the dots disappear */

    privatefinal BufferedImage DOTS_OFF = createDots(false);

    /** the image of panel background */

    privatefinal BufferedImage BACKGROUND_IMAGE = createBackground(450, 180);

    /** mission timer */

    privatefinal Timer TIMER = new Timer(500, this);

分别定义了数字的图片,点的图片,背景图片和Timer.

通过构造函数设置大小和增加鼠标监听：

    public MissionTimerPanel() {

       setPreferredSize(new Dimension(450, 180));

       setSize(new Dimension(450, 180));

       addMouseListener(this);

    }

然后是绘制数字的方法

    // create digit with given number.

    private BufferedImage createDigit(int digit) {

首先通过Java的GraphicsEnvironment取得GraphicsConfiguration,创建图片：

    GraphicsConfiguration gfxConf = GraphicsEnvironment

              .getLocalGraphicsEnvironment().getDefaultScreenDevice()

              .getDefaultConfiguration();

    BufferedImage IMAGE = gfxConf.createCompatibleImage(46, 65,

              Transparency.TRANSLUCENT);

然后创建图片的绘制样式和上下文：

       Graphics2D g2 = (Graphics2D) IMAGE.getGraphics();

       g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

              RenderingHints.VALUE_ANTIALIAS_ON);

       g2.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,

              RenderingHints.VALUE_STROKE_PURE);

       g2.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION,

              RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);

       g2.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING,

              RenderingHints.VALUE_COLOR_RENDER_QUALITY);

       g2.setRenderingHint(RenderingHints.KEY_DITHERING,

              RenderingHints.VALUE_DITHER_ENABLE);

       g2.setRenderingHint(RenderingHints.KEY_RENDERING,

              RenderingHints.VALUE_RENDER_QUALITY);

接着开始创建数字组成的线,每个数字组成都是8这个数字的一份,所以先绘制一下8所需要的所有线段：

    GeneralPath segment_a = new GeneralPath();

    segment_a.moveTo(17, 0);

    segment_a.lineTo(38, 0);

    segment_a.lineTo(37, 8);

    segment_a.lineTo(16, 8);

    segment_a.closePath();

这是其中一条,其它的也类似.

最后就是根据数字使用上面的线条绘制指定的图片了:

    case 2:

           g2.setColor(COLOR_ON);

           g2.fill(segment_a);

           g2.fill(segment_b);

           g2.fill(segment_d);

           g2.fill(segment_e);

           g2.fill(segment_g);

           g2.setColor(COLOR_OFF);

           g2.fill(segment_c);

           g2.fill(segment_f);

           g2.setColor(FRAME_COLOR_ON);

           g2.draw(segment_a);

           g2.draw(segment_b);

           g2.draw(segment_d);

           g2.draw(segment_e);

           g2.draw(segment_g);

           g2.setColor(FRAME_COLOR_OFF);

           g2.draw(segment_c);

           g2.draw(segment_f);

           break;

这是2的绘制,其它的也类似,这样就生成了所有的数字.

然后是绘制点的方法:

    private BufferedImage createDots(boolean on) {

它和绘制数字基本一致,也是通过Java的GraphicsEnvironment取得GraphicsConfiguration,创建图片,然后创建图片的绘制样式和上下文，最后画点：

    g2.setColor(COLOR_ON);

    g2.fillOval(8, 20, 7, 7);

    g2.fillOval(5, 39, 7, 7);

    g2.setColor(FRAME_COLOR_ON);

g2.drawOval(8, 20, 7, 7);

    g2.drawOval(5, 39, 7, 7);

接着是绘制背景的颜色、字和图片：

    private BufferedImage createBackground(int width, int height) {

前面创建图片和设置样式和绘制数字和点的基本一致,只是使用了LinearGradientPaint进行颜色渐变的绘制：

final LinearGradientPaint GRADIENT_HIGHLIGHT = new LinearGradientPaint(START_HIGHLIGHT, STOP_HIGHLIGHT, FRACTIONS_HIGHLIGHT, COLORS_HIGHLIGHT);

       g2.setPaint(GRADIENT_HIGHLIGHT);

       g2.fillRect(17, 79, 176, 87);

       g2.fillRect(193, 79, 239, 87);

最后把对应的显示字绘制上：

       g2.drawString("HOURS", 75, 65);

这样所有的绘制图片就结束了.

然后是处理组件的监听：

    @Override

    publicvoid mouseClicked(MouseEvent event) {

当鼠标点击组件时启动Timer,再次点击终止Timer

if (event.getButton() == MouseEvent.BUTTON1) {

           if (TIMER.isRunning()) {

              stopTimer();

           } else {

              startTimer();

           }

if (event.getClickCount() == 2) {

           resetTimer();

}

}

启动、启动和重置Timer比较简单,直接使用Timer的Start和Stop就可以了.

    publicvoid startTimer() {

       TIMER.start();

    }

重置的话还要停止Timer后再刷新一次画面.

再来就是Timer启动后触发的事件：

    @Override

    publicvoid actionPerformed(ActionEvent event) {

在这里会根据计数设置当前应该显示的图片,最后调用repaint.

    if (sec_right == 10) {

              sec_right = 0;

              sec_left++;

}

最后就是复写paintComponent方法使组件更新了：

    @Override

    protectedvoid paintComponent(Graphics g) {

首先取得绘制的上下文Graphics2D g2 = (Graphics2D) g.create();

然后设置绘制的属性和样式：

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

              RenderingHints.VALUE_ANTIALIAS_ON);

       g2.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION,

              RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);

       g2.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING,

              RenderingHints.VALUE_COLOR_RENDER_QUALITY);

       g2.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL,

              RenderingHints.VALUE_STROKE_PURE);

       g2.setRenderingHint(RenderingHints.KEY_DITHERING,

              RenderingHints.VALUE_DITHER_ENABLE);

       g2.setRenderingHint(RenderingHints.KEY_RENDERING,

              RenderingHints.VALUE_RENDER_QUALITY);

设置好颜色、锯齿、混合色、边等属性后就可以绘制了：

//背景的绘制

g2.drawImage(BACKGROUND_IMAGE, 0, 0, this);

//点的绘制

g2.drawImage(DOTS_ON, 172, 90, this);

//时分秒等的绘制

g2.drawImage(DIGIT_ARRAY[hour_left], 38, 90, this);

绘制完所有的时分秒、点之后,重写就完成了.

因为这个组件就是一个Panel,可以和正常Panel一样使用,通过new MissionTimerPanel();就可以调用了.